Method for operating a filling device with a filling valve

Abstract

Described and illustrated is a method (1) for operating a filling device (2) and a corresponding filling device (2) with a filling valve (3) for controlling a medium flow, with a magnetic-inductive flow sensor (4) for measuring the medium flow released by the filling valve (3), and with a control and evaluation unit (5) for controlling the filling valve (3), wherein the magnetic-inductive flow sensor (4) has a measuring tube (6) for guiding the medium flow, a magnetic field generating device (7) for generating a magnetic field (B) passing through the measuring tube (6) perpendicular to the flow direction of the medium flow, wherein the control and evaluation unit (5) controls the magnetic field generating device (7) such that in a standard operation (9), the magnetic field (B) changes its polarity with a standard magnetic field frequency (f_stand) as the work magnetic field frequency (f_work),wherein the control and evaluation unit (5) determines at least one flow measurement value (flow) in the interval (10) of a constant magnetic field polarity and a stable magnetic field (8) on the basis of a standard calibration (kal_stand) as a work calibration (kal_work), and wherein the control and evaluation unit (5) controls the filling valve (3) to carry out a filling process (11) with at least one plateau phase (12) of the flow and an associated plateau flow measurement value (flow_plat) with a defined target filling quantity according to a filling curve (13), wherein the filling curve (13) indicates the degree of opening (O) of the filling valve (3). Increased measurement accuracy is achieved in that, in a test phase (14), the control and evaluation unit (5) operates the magnetic field generating device (7) with a test magnetic field frequency (f_test) that is greater than the set working magnetic field frequency (f_work), wherein it is checked (15) whether a stable magnetic field (B) is also generated at the test magnetic field frequency (f_test) in an interval (10) of a constant magnetic field polarity, and that when a stable magnetic field (B) is generated, the test magnetic field frequency (f_test) is set and used as the new working magnetic field frequency (f_work).

Description

[0001] The invention relates to a method for operating a filling device with a filling valve for controlling a medium flow, with a magnetic-inductive flow sensor for measuring the medium flow released by the filling valve and with a control and evaluation unit for controlling the filling valve, wherein the magnetic-inductive flow sensor has a measuring tube for guiding the medium flow, a magnetic field generating device for generating a magnetic field passing through the measuring tube perpendicular to the flow direction of the medium flow, wherein the control and evaluation unit controls the magnetic field generating device such that in standard operation the magnetic field changes its polarity with a standard magnetic field frequency as the working magnetic field frequency,The control and evaluation unit determines at least one flow measurement value in the interval of a constant magnetic field polarity and a stable magnetic field based on a standard calibration as a working calibration. The control and evaluation unit controls the filling valve to perform a filling process with at least one plateau phase of the flow and an associated plateau flow measurement value with a defined target filling quantity according to a filling curve, the filling curve indicating the degree of opening of the filling valve. Furthermore, the invention also relates to a corresponding filling device.

[0002] Filling devices of the aforementioned type are widely used in process engineering, for example, in the chemical industry, but especially in the food and beverage industry. In principle, flow sensors based on any flow measurement principle can be used in filling devices, but in this case, we are dealing with the use of magnetic-inductive flow sensors. Magnetic-inductive flow sensors have the advantage that no mechanically moving parts are required to perform a measurement, unlike, for example, vortex flow meters or Coriolis mass flow meters. Industrially used process-engineered filling systems often feature a variety of the filling devices described above, which could also be referred to as filling stations within a filling system.

[0003] The measuring principle of magnetic-inductive flow measurement is based on the force acting on moving charge carriers in a magnetic field (Lorentz force) and the resulting charge separation in the medium flow in the area of ​​the magnetic field. For the measuring principle to function, the medium must have a minimum electrical conductivity. The separated charge carriers generate an electric field in the medium, the strength of which is proportional to the medium's velocity. Using two measuring electrodes on the circumference of the measuring tube, a measuring voltage proportional to the medium's flow can be tapped, which is then processed into a flow measurement value.

[0004] It is common practice to change the polarity of the magnetic field generated by the magnetic field generating device with a magnetic field frequency, so that the polarity of the measuring voltage received by the measuring electrodes also changes. Reasons for regularly changing the polarity of the magnetic field include the ability to eliminate parasitic electrode voltages that do not change with the polarity of the magnetic field and also to avoid electrochemical processes at the electrodes that are associated with charge carriers of constant polarity. The magnetic field frequency is typically in the range of a few tens to hundreds of Hz.

[0005] The magnetic field cannot be switched suddenly, as the change in the current supply to the magnetic field generating device takes a certain amount of time via the build-up and decay of voltage-time surfaces. The voltage of the measuring electrodes is only used to determine flow measurement values ​​when the magnetic field is stable, i.e., has a constant strength. In the interval of constant magnetic field polarity and a stable magnetic field – i.e., a magnetic field of constant strength – the measuring voltage is sampled at high frequency, usually by an A / D converter with a sampling rate that is usually orders of magnitude higher than the magnetic field frequency. A flow measurement value is then determined from the multitude of raw measurement values ​​thus obtained. The magnetic field frequency therefore also indicates the measuring rate at which the magnetic-inductive flow sensor determines and provides flow measurement values.

[0006] For flow sensors, specification values ​​such as accuracy (absolute accuracy and repeatability) and measuring range (minimum and maximum detectable flow rates) are specified for a specific operating range, such as temperature (minimum and maximum ambient and / or medium temperature). Compliance with the specification is guaranteed within the specified permissible operating range.

[0007] The operation of the flow sensor within the permissible operating range was initially referred to as standard operation, in which the flow sensor operates with a standard magnetic field frequency as the working magnetic field frequency. The flow sensor is calibrated at this standard magnetic field frequency - usually at the factory - i.e. a calibration curve is determined that describes the relationship between the measuring voltage at the electrodes and the average flow velocity of the medium through the measuring tube. The calibration curve is often a straight line with a gradient (sensor constant) and a zero point offset (electrode voltage at zero flow), but more than two points can also be used to describe the calibration curve. In standard operation, the standard calibration is used; the standard calibration is therefore the working calibration in standard operation.

[0008] When operating the flow sensor in this standard mode, for example, it is guaranteed that measured values ​​are available at a specific measuring rate in the temperature range specified as permissible. Based on the previously given explanation of the relationship between magnetic field frequency and measuring rate, this means that the magnetic field can also be generated at the required magnetic field frequency across the entire temperature range, i.e. in such a way that, with a constant magnetic field polarity, a stable magnetic field is generated over a sufficient period of time so that a sufficient amount of raw measurement data can be recorded from which the flow measurement value is then determined.

[0009] The filling device described above comprises the filling valve, the flow sensor, and the control and evaluation unit as its central components. The filling valve can be technically implemented in various ways; it can be a valve with a single controllable actuator, but it can also comprise several controllable components, for example, a combination of a switching valve and a control valve. The control and evaluation unit controls the filling valve. In the case considered here, a filling curve is followed that describes the degree of opening of the filling valve as a function of the detected filling quantity.This allows the filling process to be finely tuned. For example, a slow opening of the filling valve can be selected at the beginning of the filling process to prevent foaming or swirling of the medium. In the middle of the filling process, a large valve opening can be set constantly over a certain filling distance (plateau phase), until the end of the filling process, when the valve opening is gradually or continuously reduced. A filling process can also have several plateau phases, i.e., intervals of constant flow (plateau flow). It is assumed that the filling process always has at least one plateau phase.

[0010] Aside from the fact that the most accurate dosing of a medium is always desirable during a filling process, the accuracy of the filling process is even more important when filling containers intended for distribution to end users (bottles, canisters, cans). In this case, a minimum quantity, usually the quantity indicated on the container, must be guaranteed. Therefore, any tolerances in the filling process are always at the manufacturer's expense, thus overfilling is always a factor.

[0011] The object of the present invention is to design and further develop the method for operating the filling device and a corresponding filling device in such a way that the filling process can be carried out with increased accuracy.

[0012] The previously derived and demonstrated problem is solved in the method for operating a filling device in that, during a test phase, the control and evaluation unit operates the magnetic field device with a test magnetic field frequency that is greater than the set working magnetic field frequency. It is checked whether a stable magnetic field is also generated at the test magnetic field frequency in an interval of constant magnetic field polarity. If a stable magnetic field is generated, the test magnetic field frequency is set and used as the new working magnetic field frequency. If a stable magnetic field cannot be generated with the test magnetic field frequency, various responses are possible; for example, the starting working magnetic field frequency can simply be retained as the working magnetic field frequency.

[0013] The invention is based on the finding that standard operation is designed such that the flow sensor can operate according to specifications, i.e., even under unfavorable conditions - for example, at high temperatures where the ohmic resistance of the magnetic field generating device has increased - it can still reliably achieve a stable magnetic field at the standard magnetic field frequency and thus a correspondingly high measuring rate for determining flow measurement values. Furthermore, a flow sensor is usually designed such that, even with slight deviations from the permissible operating range, the flow sensor and thus the filling device can still operate according to specifications. Conversely, this means that under more favorable operating conditions within the operating range, the flow sensor can achieve better performance with regard to some parameters than its specifications would suggest.

[0014] The invention aims to increase the measurement rate at which flow measurements are determined, and thus to increase the working magnetic field frequency of the magnetic field beyond the standard magnetic field frequency. Increasing the working magnetic field frequency and thus the measurement rate of the flow measurements has a direct impact on improving absolute measurement accuracy as well as repeatability during filling, since the continuous flow pattern is sampled at a higher frequency, thus achieving a finer temporal resolution.

[0015] In an advantageous embodiment of the method, the check to determine whether a stable magnetic field is generated in an interval of constant magnetic field polarity is carried out by evaluating a magnetic field sensor and assessing the stationarity of the magnetic field. Additionally or alternatively, the stationarity of a current impressed into the magnetic field generating device and / or a voltage applied to the magnetic field generating device is assessed. Preferably, the stationarity of the variables is assessed by time series analysis of the detected magnetic field strength and / or the detected impressed current and / or the detected applied voltage. Known statistical deviation measures, such as the standard deviation, can be used to assess stationarity.

[0016] In a preferred embodiment of the method, the test phase is repeated several times. If a stable magnetic field can always be generated during the multiple repetitions, the working magnetic field frequency—and thus the measurement rate at which flow measurements are generated—is gradually increased. The repetitions are preferably continued until the highest test magnetic field frequency has been determined at which a stable magnetic field is generated in an interval of constant magnetic field polarity. Of course, here too, the test magnetic field frequency is set as the working magnetic field frequency if the magnetic field has proven to be stable.

[0017] In a further development of the previously described embodiment, the test magnetic field frequency is increased in constant frequency steps during the test phase repetitions (e.g., 60 Hz, 65 Hz, 70 Hz, etc.). Alternatively, the test magnetic field frequency is initially increased in larger, then smaller frequency steps (e.g., 60 Hz, 75 Hz, 85 Hz, 90 Hz, 92 Hz). In a further alternative, the test magnetic field frequency is changed according to the principle of interval nesting. In the case of interval nesting, the interval step size can, for example, be halved in each repetition of the test phase, with the jump direction depending on the result of the magnetic field stability test (e.g., the complete interval 50 Hz to 100 Hz comprises: 50 Hz (stable), 100 Hz (unstable), 75 Hz (stable), 87.5 Hz (stable), 93.75 Hz (stable), aborting if the minimum step size is not reached).

[0018] If one considers that the magnetic field frequencies, as in the given examples, are often in the range of a few 10 Hz, then it becomes clear that finding even the highest possible working magnetic field frequency takes only fractions of a second.

[0019] A further development of the method is characterized by the fact that the check for a stable magnetic field is performed without changing the magnetic field frequency—as is the case during test operation. This ensures that the working magnetic field frequency, which differs from the standard magnetic field frequency, still represents a valid operating mode. In particular, this check can be performed continuously, i.e., every time the magnetic field polarity is switched.

[0020] A further development of the process involves switching the working magnetic field frequency back to the standard magnetic field frequency and repeating the test phase from standard operation. Switching back to standard operation can occur at regular intervals or after a certain number of filling intervals, or even after it has been determined that a stable magnetic field can no longer be generated at the set working magnetic field frequency.

[0021] In a particularly advantageous embodiment of the method, the flow sensor is operated with the working magnetic field frequency deviating from the standard magnetic field frequency and the flow sensor is recalibrated by determining a test calibration curve between at least two points of known flow during the filling process and associated recorded voltage values ​​at two measuring electrodes of the flow sensor, wherein the test calibration curve is subsequently used as working calibration.

[0022] In a further development of the aforementioned method, the plateau flow rate during the plateau phase of the flow and the corresponding voltage value at the measuring electrodes of the flow sensor are used as a point of known flow. Alternatively or additionally, a zero flow rate with the filling valve closed during the filling process and the corresponding voltage value at the measuring electrodes of the flow sensor are used as another point. From the values ​​thus determined, a calibration curve can be determined with the gradient as the so-called sensor constant and the zero point offset at zero flow.

[0023] In a further development of the method described above, the zero flow is validated by checking the degree of opening of the filling valve for complete closure and / or by checking the zero flow by the flow measurement value of the flow sensor during a temporary switchback to standard operation with the standard magnetic field frequency based on the standard calibration and subsequent switch to the stable test magnetic field frequency deviating from the standard magnetic field frequency, for which the calibration curve is determined.

[0024] With regard to the process extensions with the determination of a calibration curve, a further development provides for the flow sensor to be switched to standard operation by setting the standard magnetic field frequency as the working magnetic field frequency and the standard calibration as the working calibration. Furthermore, when a filling process is subsequently carried out, a current plateau flow measurement is determined in the plateau phase of the flow. If the current plateau flow measurement deviates from the previously determined (or given) plateau flow measurement with standard calibration or from the previously determined flow measurement in the plateau phase with an increased test magnetic field frequency with the test calibration curve as the working calibration, a new test calibration curve is determined and set as the working calibration.This procedure prevents an incorrect value for the plateau flow being assumed in the event of a change in the filling behavior (e.g. due to a change in process pressure), which would also lead to incorrect calibration.

[0025] In a further advantageous embodiment of the method, at least one temperature of the flow sensor is determined; in particular, a temperature of the magnetic field generating device and / or a medium temperature of the medium flowing through the flow sensor and / or an ambient temperature of the flow sensor is determined. These temperatures all influence the flow sensor, although the immediacy of the influence varies. The use of the aforementioned temperatures is sensible because the ohmic resistance of the magnetic field generating device is significantly temperature-dependent, and the ohmic resistance is a decisive factor in determining which voltages and currents can be impressed into the magnetic field generating device. The ohmic resistance therefore determines the time behavior of the switching of the magnetic fields of interest.Depending on the at least one temperature of the flow sensor, a starting test magnetic field frequency is determined and used as the test magnetic field frequency during the test phase. This frequency is close to the maximum stable test magnetic field frequency achievable at the determined temperature of the flow sensor. The starting test magnetic field frequency can be meaningfully selected at which temperature, and the relationship between the starting test magnetic field frequency and the at least one determined temperature of the flow sensor, can be determined empirically, for example, particularly for a specific type of flow sensor or filling device.

[0026] As mentioned at the beginning, filling plants often have a plurality of the previously described filling devices. In this context, a further advantageous embodiment of the method has the feature that the working magnetic field frequency and / or test calibration curve determined for a specific flow sensor in a specific filling device are transferred as a working calibration to other flow sensors in other filling devices, in particular to other flow sensors in other filling devices that are operated together with the specific filling device in a filling plant.

[0027] The described object is also achieved with a corresponding and previously described filling device with a filling valve for controlling a medium flow, with a magnetic-inductive flow sensor for measuring the medium flow released by the filling valve and with a control and evaluation unit for controlling the filling valve, wherein the control and evaluation unit controls the filling valve to carry out a filling process with a defined target filling quantity according to a filling curve, wherein the filling curve indicates the degree of opening of the filling valve, wherein the magnetic-inductive flow sensor has a measuring tube for guiding the medium flow, a magnetic field generating device for generating a magnetic field passing through the measuring tube perpendicular to the flow direction of the medium flow, wherein the control and evaluation unit controls the magnetic field generating device in such a way,that in standard operation, the magnetic field changes its polarity with a standard magnetic field frequency as the working magnetic field frequency, wherein the control and evaluation unit determines at least one flow measurement value in the interval of a constant magnetic field polarity and a stable magnetic field on the basis of a standard calibration as the working calibration, achieved in that the control and evaluation unit is designed and configured such that it carries out the method described in detail above, including its further developments, during operation of the filling device.

[0028] In detail, there are now numerous possibilities for designing and developing the method according to the invention for operating a filling device and the filling device according to the invention. Reference is made, on the one hand, to the claims subordinate to the independent patent claims and, on the other hand, to the following description of exemplary embodiments in conjunction with the drawings. The drawings show: Fig. 1 schematically shows a method for operating a filling device together with such a filling device as is known from the prior art, Fig. 2 schematically shows the switching of the polarity of the magnetic field of the flow sensor, Fig. 3 schematically shows the change of the magnetic field frequency and test for a stable magnetic field in a test phase, Fig. 4 schematically shows the multiple repetition of the test phase for the purpose of systematically increasing the magnetic field frequency and Fig. 5 schematically shows the recalibration of the flow sensor.

[0029] In the Fig. 1 to 5 schematically show in various forms and in various levels of detail the method 1 for operating a filling device 2 with a filling valve 3 for controlling a medium flow, with a magnetic-inductive flow sensor 4 for measuring the medium flow released by the filling valve 3 and with a control and evaluation unit 5 for controlling the filling valve 3, as well as corresponding filling devices 2.

[0030] Fig. 1 shows the method 1 for operating a filling device 2 and such a filling device 2, as are known from the prior art. The magnetic-inductive flow sensor 4 has a measuring tube 6 for guiding the medium flow, a magnetic field generating device 7 for generating a magnetic field B that passes through the measuring tube 6 perpendicular to the flow direction of the medium flow. The control and evaluation unit 5 controls the magnetic field generating device 7 such that, in standard operation 9, the magnetic field B changes its polarity with a standard magnetic field frequency f_stand as the work magnetic field frequency f_work, wherein the control and evaluation unit 5 determines at least one flow measurement value flow in the interval 10 of a constant magnetic field polarity and a stable magnetic field B on the basis of a standard calibration kal_stand as the work calibration kal_work.

[0031] The control and evaluation unit 5 controls the filling valve 3 to carry out a filling process 11 with at least one plateau phase 12 of the flow and an associated plateau flow measurement value flow_plat with a defined target filling quantity according to a filling curve 13. The filling curve 13 indicates the degree of opening O of the filling valve 3. The filling curve 13 is in Fig. 1 plotted against the filling quantity V. The filling quantity V is obtained by integrating the flow measurement values ​​flow over time. If the process conditions remain constant, then the filling curve 13 could also be plotted against time, which is Fig. 1 is indicated.

[0032] Standard operation 9 is characterized by the use of standard parameters (f_stand, kal_stand) with which the flow sensor 4 and thus the filling device 2 have been calibrated at the factory. The flow sensor 4 is designed to determine flow measurement values ​​flow within the specified operating range (e.g., a temperature range) within the scope of its applicable specifications, for example, at a specific measuring rate and with a specific accuracy.

[0033] The control and evaluation unit 5 serves to control the filling valve 3, but it also serves to control the magnetic-inductive flow sensor 4 and to evaluate the raw measurement data received from the flow sensor 4 and to determine flow measurement values ​​flow. In Fig. In Figure 1, the control and evaluation unit 5 is depicted as a single unit, but this is not important. Typically, such control and evaluation units 5 are implemented in hardware based on microcontrollers and / or digital signal processors. Whether the control and evaluation unit 5 is implemented as a single device module or by means of several device modules that communicate with each other is irrelevant for the description of the method 1 and the filling device 2 of interest here.

[0034] Fig. Figure 2 shows the temporal progression of the magnetic field B generated by the magnetic field generating device 7. In standard operation, the polarity of the magnetic field B is switched at the standard magnetic field frequency f_stand. Three switching intervals 10' of the magnetic field polarity are shown, which are almost identical to the intervals 10 of constant magnetic field polarity. If the polarity of the voltage at the magnetic field generating device 7 is changed at the beginning of the switching interval 10', it takes a certain amount of time for the magnetic field B to first decay in one direction and then build up in the other direction. The time until the magnetic field B has completely decayed from one polarity is the time offset between the interval of constant magnetic field polarity 10 and the switching interval 10'.In any case, it is important that for the calculation of flow measurement values ​​flow only voltages at the measuring electrodes 8 can be used if the magnetic field B is stable, i.e. has reached a constant and predetermined level.

[0035] In Fig. 2 indicates the intervals in which the magnetic field B meets these stability requirements (B! = stable). The sampled voltages at the measuring electrodes 8, indicated by the arrows in these time ranges, can be used to calculate a flow measurement value flow in each interval. The measuring rate at which the flow sensor 4 generates flow measurement values ​​flow therefore depends directly on the magnetic field frequency at which the magnetic field B changes its polarity.

[0036] Fig. 3 shows a method 1 that aims to increase the magnetic field frequency compared to the original calibration in order to increase the measuring rate for the flow measurement of the flow sensor 4 and thus improve the measurement accuracy and repeatability of the flow sensor 4. The starting point is standard operation 9. In a subsequent test phase 14, the control and evaluation unit 5 operates the magnetic field generating device 7 with a test magnetic field frequency f_test that is greater than the set working magnetic field frequency f_work. A check 15 (B?=stable) is then performed to determine whether a stable magnetic field B is also generated at the test magnetic field frequency f_test in an interval 10 of constant magnetic field polarity. If a stable magnetic field B is generated, the test magnetic field frequency f_test is set and used as the new working magnetic field frequency f_work.If a stable magnetic field cannot be achieved at the higher magnetic field frequency, the old work magnetic field frequency f_work_alt, in this case the standard magnetic field frequency, is reset as the work magnetic field frequency f_work in the illustrated embodiment.

[0037] The check 15 as to whether a stable magnetic field B is generated in an interval 10 of a constant magnetic field polarity is carried out by assessing the stationarity of a current impressed into the magnetic field generating device 7 and a voltage applied to the magnetic field generating device 7, in this case by time series analysis of the detected impressed current and the detected applied voltage.

[0038] In the procedure according to Fig. 4, test phase 14 is repeated several times, in this case until the largest test magnetic field frequency f_test has been determined, at which a stable magnetic field B is generated in an interval 10 of constant magnetic field polarity, whereby this test magnetic field frequency f_test is then naturally set as the work magnetic field frequency f_work. When repeating test phase 14, the test magnetic field frequency f_test is increased in constant frequency steps. As in Fig. 3 is in Fig. 4 the identifier f_work_old was introduced to keep the old work magnetic field frequency available in order to be able to access the value again in case of a necessary step back.

[0039] The method 1 is designed here such that the test phase 14 is not repeated as soon as a maximum test magnetic field frequency f_test has been found and set as the work magnetic field frequency f_work.

[0040] Furthermore, method 1 is configured such that the working magnetic field frequency f_work is switched back to the standard magnetic field frequency f_stand, and the test phase 14 is run through again starting from standard operation 9, with the switchback to standard operation 9 occurring at regular intervals. This ensures that a set working magnetic field frequency f_work, at which reliable operation of the flow sensor 4 is no longer possible—for whatever reason—is detected, and a safe fallback position, namely standard operation 9, is reset.

[0041] Procedure 1 according to Fig.5 is characterized in that the flow sensor 4 is operated with the working magnetic field frequency f_work, which deviates from the standard magnetic field frequency f_stand, and the flow sensor 4 is recalibrated 16 by determining a test calibration curve 17 between two points of known flow flow1, flow2 during the filling process 11 and the associated detected voltage values ​​U1, U2 at two measuring electrodes 8 of the flow sensor 4, wherein the test calibration curve 17 is used as the working calibration kal_work. In other embodiments, a calibration is performed with more than two calibration points.

[0042] In the present case, the plateau flow flow_plat during the plateau phase 12 of the flow and the associated voltage value U1 at the measuring electrodes of the flow sensor 4 are used as a point of known flow flow1, and a zero flow flow2 with the filling valve 3 closed during the filling process 11 and the associated voltage value U2 at the measuring electrodes 8 of the flow sensor 4 are used as a second point.

[0043] In addition, it is realized that the zero flow is validated by checking the opening degree O of the filling valve 3 for complete closure.

[0044] In one embodiment of the method 1, the flow sensor 4 is switched to standard operation 9 by setting the standard magnetic field frequency f_stand as the work magnetic field frequency f_work and the standard calibration kal_stand as the work calibration kal_work, wherein upon subsequent execution of a filling process 11, a current plateau flow measurement value is determined in the plateau phase 12 of the flow, wherein in the event of a deviation of the current plateau flow measurement value from the previously determined or given plateau flow measurement value flow_plat with standard calibration kal_stand or from the previously determined flow measurement value flow_plat in the plateau phase 12 with increased test magnetic field frequency f_test with the test calibration curve 17 as the work calibration kal_work, a new test calibration curve 17 is determined and set as the work calibration kal_work.This procedure variant ensures that plateau flow measurement values ​​flow_plat that were assumed to be valid but are no longer applicable are recognized as incorrect and corrected.

[0045] In a further development of method 1, at least one temperature T of the flow sensor 4 is determined, in particular a temperature T of the magnetic field generating device 7 and / or a medium temperature of the medium flowing through the flow sensor 4 and / or an ambient temperature of the flow sensor 4, wherein, depending on the at least one temperature T of the flow sensor 4, in the test phase 14, a start test magnetic field frequency f_test_start is determined and used as the test magnetic field frequency f_test, which is close to the maximum stable test magnetic field frequency f_test achievable at the determined temperature T of the flow sensor 4, in particular wherein the dependence of the start test magnetic field frequency f_test_start on the at least one determined temperature T of the flow sensor 4 has been determined empirically, in particular for a specific type of flow sensor 4 or a specific type of filling device 2.

[0046] If the method 1 is used in a filling plant with many similar filling devices 2, then in an advantageous embodiment it is provided that the work magnetic field frequency f_work and / or test calibration curve 17 determined for a specific flow sensor 4 in a specific filling device 2 are transferred as work calibration kal_work to other flow sensors 4 in other filling devices 2, in particular to other flow sensors 4 in other filling devices 2 that are operated in a filling plant together with the specific filling device 2.

[0047] As a result, the described method 1 and the correspondingly designed filling devices 2 lead to an improvement in the absolute accuracy and repeatability of the measurement, so that filling processes can be carried out with lower safety margins and thus with lower raw material requirements. Reference symbol 1 procedure 2 filling device 3 Filling valve 4 magnetic-inductive flow sensor 5 Control and evaluation unit 6 measuring tube 7 Magnetic field generating device 8 measuring electrodes 9 Standard operation 10 Interval of constant magnetic field polarity 10' switching interval of the magnetic field polarity 11 Filling process 12 Plateau phase of flow 13 Filling curve 14 Test phase 15 Checking for a stable magnetic field 16 Recalibration of the flow sensor 17 Test calibration curve B Magnetic field U electrical voltage at the measuring electrodes f_stand Standard magnetic field frequency f_work work-magnetic field frequency f_test test magnetic field frequency kal_stand Standard calibration kal_work Work calibration flow flow measurement value flow_plat Plateau flow measurement value O Degree of opening of the filling valve stable magnetic field flow1, flow measurements for recalibration flow2 U1, U2 Measuring electrode voltages at flow1, flow2

Claims

[1] Method (1) for operating a filling device (2) with a filling valve (3) for controlling a medium flow, with a magnetic-inductive flow sensor (4) for measuring the medium flow released by the filling valve (3) and with a control and evaluation unit (5) for controlling the filling valve (3), wherein the magnetic-inductive flow sensor (4) has a measuring tube (6) for guiding the medium flow, a magnetic field generating device (7) for generating a magnetic field (B) passing through the measuring tube (6) perpendicular to the flow direction of the medium flow, wherein the control and evaluation unit (5) controls the magnetic field generating device (7) such that in a standard operation (9) the magnetic field (B) changes its polarity with a standard magnetic field frequency (f_stand) as the work magnetic field frequency (f_work),wherein the control and evaluation unit (5) determines at least one flow measurement value (flow) in the interval (10) of a constant magnetic field polarity and a stable magnetic field (8) on the basis of a standard calibration (kal_stand) as a work calibration (kal_work), and wherein the control and evaluation unit (5) controls the filling valve (3) to carry out a filling process (11) with at least one plateau phase (12) of the flow and an associated plateau flow measurement value (flow_plat) with a defined target filling quantity according to a filling curve (13), wherein the filling curve (13) indicates the degree of opening (O) of the filling valve (3), characterized by , that in a test phase (14) the control and evaluation unit (5) operates the magnetic field generating device (7) with a test magnetic field frequency (f_test) which is greater than the set working magnetic field frequency (f_work), wherein it is checked (15) whether a stable magnetic field (B) is also generated at the test magnetic field frequency (f_test) in an interval (10) of a constant magnetic field polarity and that when generating a stable magnetic field (B), the test magnetic field frequency (f_test) is set and used as the new work magnetic field frequency (f_work). [2] Method (1) according to claim 1, characterized bythat the check (15) as to whether a stable magnetic field (B) is generated in an interval (10) of a constant magnetic field polarity is carried out by evaluating a magnetic field sensor and assessing the stationarity of the magnetic field (B), and / or by assessing the stationarity of a current impressed into the magnetic field generating device (7) and / or a voltage applied to the magnetic field generating device (7), in particular by time series analysis of the detected magnetic field strength and / or the detected impressed current and / or the detected applied voltage. [3] Method (1) according to claim 1 or 2, characterized bythat the test phase (14) is repeated several times, in particular until the largest test magnetic field frequency (f_test) has been determined at which a stable magnetic field (B) is generated in an interval (10) of a constant magnetic field polarity, this test magnetic field frequency (f_test) being set as the work magnetic field frequency (f_work). [4] Method (1) according to claim 3, characterized by that the test magnetic field frequency (f_test) is increased in constant frequency steps or that the test magnetic field frequency (f_test) is initially increased in large, then in smaller frequency steps, or that the test magnetic field frequency (f_test) is changed according to the principle of interval nesting. [5] Method (1) according to one of claims 1 to 4, characterized bythat the work magnetic field frequency (f_work) is switched back to the standard magnetic field frequency (f_stand) and the test phase (14) is run through again starting from the standard operation (9), in particular wherein the switching back to the standard operation (9) takes place at regular time intervals or filling intervals. [6] Method (1) according to one of claims 1 to 5, characterized by that the flow sensor (4) is operated with the work magnetic field frequency (f_work) deviating from the standard magnetic field frequency (f_stand) and the flow sensor (4) is recalibrated (16) by determining a test calibration curve (17) between at least two points of known flow (flow1, flow2) during the filling process (11) and associated recorded voltage values ​​(U1, U2) at two measuring electrodes (8) of the flow sensor (4), wherein the test calibration curve (17) is used as work calibration (kal_work). [7] Method (1) according to claim 6, characterized bythat the plateau flow (flow_plat) during the plateau phase (12) of the flow and the associated voltage value (U1) at the measuring electrodes of the flow sensor (4) are used as a point of known flow (flow1) and / or that a zero flow (flow2) with the filling valve (3) closed during the filling process (11) and the associated voltage value (U2) at the measuring electrodes (8) of the flow sensor (4) are used as another point. [8] Method (1) according to claim 7, characterized bythat the zero flow is validated by checking the degree of opening (O) of the filling valve (3) for complete closure and / or by checking the zero flow by the flow measurement value (flow) of the flow sensor (4) with a temporary switch back to standard operation (9) with the standard magnetic field frequency (f_stand) and subsequent change to the stable test magnetic field frequency (f_test) deviating from the standard magnetic field frequency (f_stand), for which the calibration curve is determined. [9] Method (1) according to one of claims 6 to 8, characterized bythat the flow sensor (4) is switched to standard operation (9) by setting the standard magnetic field frequency (f_stand) as the work magnetic field frequency (f_work) and the standard calibration (kal_stand) as the work calibration (kal_work), that when a filling process (11) is subsequently carried out, a current plateau flow measurement value is determined in the plateau phase (12) of the flow, wherein in the event of a deviation of the current plateau flow measurement value from the previously determined or given plateau flow measurement value (flow_plat) with standard calibration (kal_stand) or from the previously determined flow measurement value (flow_plat) in the plateau phase (12) with increased test magnetic field frequency (f_test) with the test calibration curve (17) as the work calibration (kal_work), a new test calibration curve (17) is determined and used as the work calibration (kal_work) is set. [10] Method (1) according to one of claims 1 to 9, characterized bythat at least one temperature (T) of the flow sensor (4) is determined, in particular a temperature (T) of the magnetic field generating device (7) and / or a medium temperature of the medium flowing through the flow sensor (4) and / or an ambient temperature of the flow sensor (4), that as a function of the at least one temperature (T) of the flow sensor (4) in the test phase (14), a start test magnetic field frequency is determined and used as the test magnetic field frequency (f_test), which is close to the maximum stable test magnetic field frequency (f_test) achievable at the determined temperature (T) of the flow sensor (4), in particular wherein the dependence of the start test magnetic field frequency on the at least one determined temperature (T) of the flow sensor (4) has been determined empirically, in particular for a specific type of flow sensor (4) or filling device (2). [11] Method (1) according to one of claims 1 to 10, characterized by that the work magnetic field frequency (f_work) and / or test calibration curve (17) determined for a specific flow sensor (4) in a specific filling device (2) are transferred as work calibration (kal_work) to other flow sensors (4) in other filling devices (2), in particular to other flow sensors (4) in other filling devices (2) that are operated in a filling plant together with the specific filling device (2). [12] Filling device (2) with a filling valve (3) for controlling a medium flow, with a magnetic-inductive flow sensor (4) for measuring the medium flow released by the filling valve (3) and with a control and evaluation unit (5) for controlling the filling valve (3), wherein the magnetic-inductive flow sensor (4) has a measuring tube (6) for guiding the medium flow, a magnetic field generating device (7) for generating a magnetic field (B) passing through the measuring tube (6) perpendicular to the flow direction of the medium flow, wherein the control and evaluation unit (5) controls the magnetic field generating device (7) such that in a standard operation (9) the magnetic field (B) changes its polarity with a standard magnetic field frequency (f_stand) as the work magnetic field frequency (f_work),wherein the control and evaluation unit (5) determines at least one flow measurement value (flow) in the interval (10) of a constant magnetic field polarity and a stable magnetic field (8) on the basis of a standard calibration (kal_stand) as a work calibration (kal_work), and wherein the control and evaluation unit (5) controls the filling valve (3) to carry out a filling process (11) with at least one plateau phase (12) of the flow and an associated plateau flow measurement value (flow_plat) with a defined target filling quantity according to a filling curve (13), wherein the filling curve (13) indicates the degree of opening (O) of the filling valve (3), , characterized by that the control and evaluation unit is designed and configured such that it carries out the method according to one of claims 1 to 11 during operation of the filling device.

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